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t-tellez · May 10, 2009, 08:46 PM

Hello. We are installing a new stage lighting system and some additional amplifiers to our sound system. The sound and lighting techs have asked for ten 40 amp circuits. I personally think this is too many circuits for what they are installing, but they want room for future expansion. If I am running wire in conduit from the main panel box 100 feet away to a new sub-panel box, what size wire do I need? And what size conduit do I need for this wire? Thanks

Missouri Bound · May 10, 2009, 09:04 PM

40 amp circuits? To what termination? #8 wire is rated to 45 amps. But depending on how many wires in a conduit, that rating will be derated. If these items are plug-ins, then each one will be rated. That needs to be determined first, then the wiring needs can be properly applied.

t-tellez · May 10, 2009, 09:12 PM

They will be terminated at plugs in the ceiling for the dimmer units. We have 4 dimmer units that are 2400 watt max 120 volt each. Each dimmer will be on a circuit by itself. 6 of these 40 amp circuits are for dimmers (2 circuits for future dimmers)

As far as the amps for the sound system go, they requested four 40 amp circuits. These circuits will terminate in plugs by the amps. I know the equip is 120, but as for wattage, I don't know.

All circuits will come to the main sub panel, then go to each plug from there. I was told to run #2 wire from the service panel to the new sub-panel (100' away from the service panel). I just want to be sure.

Missouri Bound · May 10, 2009, 09:20 PM

Well... there is a problem with the numbers. A 120 volt, 20 amp circuit is maxed out at 2400 watts. (same as the dimmer) You can't use these dimmers on any circuit over 20 amps, and they should be derated for continuous rate (80%)

If the amps are 120v, they won't require 40 amp circuits... it just isn't done.

Find out the equipment specs. Have your techs be specific as to what the equipment requires... then base your installation on that info.

t-tellez · May 10, 2009, 09:29 PM

Yes, I need to get more info on the sound equip.

I do think that they are asking for too big of circuits, because we don't have any 220 equipment.

For a 2400 watt dimmer, what would I use?

stanfortyman · May 10, 2009, 10:06 PM

Originally Posted by t-tellez

For a 2400 watt dimmer, what would I use?

A telephone! Call an electrician.

You are obviously unqualified to be doing this work in this setting.

Are you a licensed electrician? Insured? I don't think you would be coming to a "Home & Garden" DIY site asking questions on how to wire commercial lighting and sound systems if you were.